The objective of this study is to assess the ability of subcutaneous Gonal-F in combination with intramuscular human gonadotrophin (hCG) to initiate spermatogenesis and achieve a density of mature sperm cells of >1.5 million per ml in men with idiopathic hypogonadotropic hypogonadism and to determine the safety and tolerance of Gonal-F administered in combination with hCG in this patient population for 18 months.